Insertion of Etch Stopper Layer for OLED Advanced Patterning

This application claims priority to U.S. Provisional Patent Application Ser. No. 63/633,187 filed on Apr. 12, 2024, which is herein incorporated by reference in its entirety

Embodiments described herein generally relate to a display. More specifically, embodiments described herein relate to sub-pixel circuits and methods of forming sub-pixel circuits that may be utilized in a display such as an organic light-emitting diode (OLED) display.

Input devices including display devices may be used in a variety of electronic systems. An organic light-emitting diode (OLED) is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of an organic compound that emits light in response to an electric current. OLED devices are classified as bottom emission devices if light emitted passes through the transparent or semi-transparent bottom electrode and substrate on which the panel was manufactured. Top emission devices are classified based on whether or not the light emitted from the OLED device exits through the lid that is added following the fabrication of the device. OLEDs are used to create display devices in many electronics today. Today's electronics manufacturers are pushing these display devices to shrink in size while providing higher resolution than just a few years ago.

Therefore, a need exists for sub-pixel circuits and methods of forming sub-pixel circuits.

In one embodiment, a sub-pixel is provided. The sub-pixel includes adjacent pixel structures disposed over a substrate and exposing a metal-containing layer of an anode, adjacent overhang structures disposed over an upper surface of the pixel structures, the overhang structures define the sub-pixel and include a first structure disposed over the upper surface of pixel structures, the first structure having a first composition, and a second structure disposed over the first structure, the second structure including an extension extending laterally past a sidewall of first structure, and a protective layer disposed between the pixel structures and the first structure of the overhang structures, the protective layer includes a metal-containing material having a greater etch resistivity than the first composition of the first structure, an organic light-emitting diode (OLE) material disposed over the anode, and a cathode disposed over the OLE material.

In another embodiment, a sub-pixel circuit is provided. The sub-pixel includes pixel structures disposed over a substrate, the pixel structures exposing a metal-containing layer of an anode, overhang structures disposed over an upper surface of the pixel structures, the overhang structures define a plurality of sub-pixels and include a first structure disposed over the upper surface of pixel structures, the first structure comprising a first composition, and a second structure disposed over the first structure, the second structure including an extension extending laterally past a sidewall of first structure, and a protective layer disposed between the pixel structures and the first structure of the overhang structures, the protective layer includes a metal-containing material having a greater etch resistivity than the first composition of the first structure, an organic light-emitting diode (OLE) material disposed over the anode, and a cathode disposed over the OLE material.

In another embodiment, a method of forming a sub-pixel is provided. The method includes depositing a protective material, a first structure layer, and a second structure layer over a substrate, adjacent pixel structures are disposed over the substrate and expose a metal-containing layer of an anode, disposing and patterning a resist over the second structure layer to expose a pixel opening, conducting an etching process to remove the second structure layer of the pixel opening to form a second structure of adjacent overhang structures, conducting a first etching process to remove the first structure layer of the pixel opening to form a first structure of the adjacent overhang structures, the protective material is resistant to a first etch chemistry of the first etching process, and conducting a second etching process to remove the protective material of the pixel opening to form a protective layer disposed between the pixel structures and the first structure of the adjacent overhang structures, the metal-containing layer of the anode is resistant to a second etch chemistry of the second etching process.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.

Embodiments described herein generally relate to a display. More specifically, embodiments described herein relate to sub-pixel circuits and methods of forming sub-pixel circuits that may be utilized in a display such as an organic light-emitting diode (OLED) display.

are schematic, cross-sectional views of a sub-pixel circuit. The sub-pixel circuitofhas a pixel structure arrangementA. The sub-pixel circuitofhas a second pixel structure arrangementB. The pixel structure arrangementA includes pixel structures (PS)above an anode. The second pixel structure arrangementB includes PSon the same plane as the anode. The sub-pixel circuitincludes a substrate. The anodeincludes at least one metal-containing layer disposed over, and in some embodiments on, the substrate. The anode includes an anode layer stack disposed over, and in some embodiments on, the substrate. The anodeis defined by adjacent PSdisposed over, and in some embodiments on, the substrate. The anode layer includes a first metal-containing layer, a second metal-containing layerdisposed on the first metal-containing layer, and a third metal-containing layerdisposed on the second metal-containing layer. The first metal-containing layerand the third metal-containing layerinclude the same metal-containing material, in some embodiments. For example, the first metal-containing layerand the third metal-containing layerinclude indium tin oxide (ITO), and the second metal-containing layerincludes silver. The metal-containing materials of the first, second, and third metal-containing layers,,include, but are not limited to, chromium, titanium, gold, silver, copper, aluminum, ITO, indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), or combinations thereof.

The plurality of PSare disposed over, and in some embodiments on, the substrate. The PSinclude one of an organic material, an organic material with an inorganic coating disposed thereover, or an inorganic material. The organic material of the PSincludes, but is not limited to, polyimides. The inorganic material of the PSincludes, but is not limited to, silicon oxide (SiO), silicon nitride (SiN), silicon oxynitride (SiNO), magnesium fluoride (MgF), or combinations thereof. Adjacent PS expose and define the anode. I.e., the third metal-containing layerof the anode layer stack is exposed by the PS. The sub-pixel circuithas a plurality of sub-pixelsincluding at least a first sub-pixelA and a second sub-pixelB. While the Figures depict the first sub-pixelA and the second sub-pixelB, the sub-pixel circuitof the embodiments described herein may include two or more sub-pixels, such as a third and a fourth sub-pixel. Each sub-pixelhas organic light emitting (OLE) materials configured to emit a white, red, green, blue, white, yellow or other color light when energized. E.g., the OLE materials of the first sub-pixelA emits a red light when energized, the OLE materials of the second sub-pixelB emits a green light when energized, the OLE materials of a third sub-pixel emits a blue light when energized, and the OLE materials of a fourth sub-pixel emits another color light when energized.

The sub-pixel circuitincludes a plurality of overhang structures. Each sub-pixelis defined by adjacent overhang structures. The overhang structuresare permanent to the sub-pixel circuit. The overhang structureshave overhangs. Each overhangare defined by an extensionof a second structureextending laterally past an upper surfaceof a first structure. The first structuresare disposed over the PS. The first structureincludes a conductive material or a non-conductive inorganic material. The second structureincludes a conductive material or a non-conductive inorganic material. The conductive material includes aluminum (Al), aluminum neodymium (AlNd), molybdenum (Mo), molybdenum tungsten (MoW), copper (Cu), titanium (Ti), chromium (Cr), a transparent conductive oxide (TCO) material, or combination thereof. The TCO material includes, but is not limited to, indium zinc oxide (IZO), indium tin oxide (ITO), indium gallium zinc oxide (IGZO), or combinations thereof. The non-conductive inorganic material includes silicon nitride (SiN), silicon oxide (SiO), silicon oxynitride (SiNO), or combinations thereof. The first structureand the second structure include a different composition of material. The overhang structuresare able to remain in place, i.e., are permanent.

A protective layeris disposed between the first structuresand the PS. The protective layerprevents damage to the metal-containing layer of the anode, during etching of a first structure layerto form the first structures. During etching of the first structure layera first etch chemistry is used. The first etch chemistry may be a wet etch chemistry or a dry etch chemistry. In some embodiments, the wet etch chemistry of the first etch chemistry is acidic. In other embodiments, the first etch chemistry includes, but is not limited to, tetramethylammonium hydroxide (TMAH) or an ammonia-peroxide mixture (APM). The protective layerhas lower etch rate than the first structureswhen exposed to the first etch chemistry. E.g., the protective layeris an etch stop layer. For example, the protective layeris resistant to an acidic wet etch chemistry.

The protective layeris etchable via a second etch chemistry. The second etch chemistry is different from the first etch chemistry. The second etch chemistry may be a wet etch chemistry or a dry etch chemistry. The wet etch chemistry of the second etch chemistry includes, but is not limited to, acid, hydrogen peroxide (HO), TMAH, or APM. The second etch chemistry will not etch the metal-containing layer of the anode.

The overhang extensionsof the second structures forms the overhangsand enables the second structuresto shadow the first structures. The shadowing of the overhangsprovides for evaporation deposition of an OLE materialand a cathode. The OLE materialmay include one or more of a HIL, a HTL, an EML, and an ETL. The OLE materialis disposed over, and in some embodiments in contact with, the metal-containing layer of the anode. The OLE materialis disposed under the overhangs, i.e., the shadow of the second structures. The cathodeincludes a conductive material, such as a metal. E.g., the cathodeincludes, but is not limited to, silver, magnesium, chromium, titanium, aluminum, ITO, or combinations thereof. The cathodemay include a different material than both of the second structuresand the first structures. The cathodemay include a different material than one of the second structuresand the first structures. The cathodeis disposed over, and in some embodiments in contact with, the OLE material. The cathode, in some embodiments, contacts a sidewall of the first structures. In other embodiments, the cathodehas an endpoint before the first structures. I.e., the cathodedoes not contact the sidewall of the first structures.

Each sub-pixelincludes an encapsulation layer. The encapsulation layermay be or may correspond to a local passivation layer. The encapsulation layerof a respective sub-pixel is disposed over the cathode(and OLE material) with the encapsulation layerextending under at least a portion of each of the overhangs. The encapsulation layerincludes the non-conductive inorganic material, such as the silicon-containing material. The encapsulation layeris disposed over the cathode, where the encapsulation layerextends under at least a portion of the overhang structurespast the cathodealong the sidewall of the first structures, and contacts the bottom surface of the second structuresof the overhang structures.

are schematic, cross-sectional views of overhang structures. The overhang structuresofhas a first overhang arrangementA. The overhang structuresofhas a second overhang arrangementB. The overhang structuresof the sub-pixel circuitmay include one of the first overhang arrangementA or the second overhang arrangementB. The first overhang arrangementA include a first adhesion layerin contact with the PS, the protective layerin contact with the first adhesion layer, the first structurein contact with the protective layer, and the second structurein contact with the first structure. The first adhesion layeradheres the protective layerto the PS. In the second overhang arrangementB, the first adhesion layeris in contact with the PS, the protective layeris in contact with the first adhesion layer, the first structureis in contact with the protective layer, and a second adhesion layeris in contact with the second structure. In some embodiments, the first structureand the second structureinclude the conductive material. The first structureand the second structure include a different composition of material. The protective layerincludes a metal-containing material having an etch resistivity to the first etch chemistry greater than the etch resistivity of the conductive material of the first structuresto the first etch chemistry.

The protective layerincludes, but is not limited to, copper, copper alloy, Ti, Ti alloy, TiN, Mo, MoN, Mo alloy, TCO, or combinations thereof. The protective layerincludes a material of a different composition than the first adhesion layerand the second adhesion layer. In one example, the first overhang arrangementA includes the first adhesion layerof Mo, the protective layerof Cu or Cu alloy, the first structureof Mo, and the second structure of Ti. In another example, the second overhang arrangementB includes the first adhesion layerof Mo, the protective layerof Cu or Cu alloy, the first structureof Al, the second adhesion layerof Mo, and the second structure of Ti. The first adhesion layeris an optional layer. In some embodiments, (right of) the protective layerand the first adhesion layerinclude a width less than a width of the bottom surface of the first structure. In other embodiments, (left of) the protective layerand the first adhesion layerinclude a width greater than a width of the bottom surface of the first structure.

are schematic, cross-sectional views of a sub-pixelduring a method for forming the sub-pixel circuit. At a first operation, as shown in FIG.A, a protective material, a first structure layer, and a second structure layerare deposited over the substrate. The protective materialis disposed over the PSand the anode. The second structure layeris disposed over the first structure layer. The first structure layercorresponds to the first structureand the second structure layercorresponds to the second structureof the overhang structures. In embodiments including the first adhesion layer, the first adhesion layeris disposed between the protective materialand the PS. In embodiments including the second adhesion layer, the second adhesion layeris disposed between the first structure layerand the second structure layer.

At a second operation, as shown in, a resistis disposed and patterned. The resistis disposed over the second structure layer. The patterning is one of a photolithography, digital lithography process, or laser ablation process. The resistis then exposed to a developer such that the resistis patterned. The resistis patterned to form a pixel openingof a sub-pixel. At a third operation, as shown in, an etching process is performed. The etching process removes the second structure layerin the pixel openingto form the second structure. The second adhesion layerexposed by the pixel openingis also removed. An upper portionof the first structure layerexposed by the pixel openingis removed by the etching process. At a fourth operation, as shown in, a first etch process is performed. The first etch process may be a wet or dry etch process. The first etch process removes a lower portion, i.e., the remaining first structure layerexposed by the pixel opening. A first etch chemistry is used. The first etch chemistry may be a wet etch chemistry or a dry etch chemistry. In some embodiments, the wet etch chemistry of the first etch chemistry is acidic. In other embodiments, the first etch chemistry includes, but is not limited to, tetramethylammonium hydroxide (TMAH) or an ammonia-peroxide mixture (APM). The protective layeris lower etch rate than the first structureswhen exposed to the first etch chemistry. E.g., the protective layeris an etch stop layer.

At a fifth operation, as shown in, a second etch process is performed. A second etch chemistry is used. The second etch chemistry is different from the first etch chemistry. The first etch chemistry may be a wet etch chemistry or a dry etch chemistry. The wet etch chemistry of the second etch chemistry includes, but is not limited to, acid, hydrogen peroxide (HO), TMAH, or APM. The first adhesion layerexposed by the pixel openingis also removed by the second etch process.

At a sixth operation, as shown in, the OLE material, the cathode, and the encapsulation layerare deposited. The shadowing of the overhangprovides for evaporation deposition each of the OLE materialand a cathode. The shadowing effect of the overhang structuresdefine the OLED angle θof the OLE materialand the cathode angle θof the cathode. The OLED angle θof the OLE materialand the cathode angle θof the cathoderesult from evaporation angle set by the evaporation source and the extensionof the second structuresextending laterally past the upper surfaceof the first structures. The encapsulation layeris disposed over the cathode(and OLE material) with the encapsulation layerextending under at least a portion of each of the overhangs. The encapsulation layerincludes the non-conductive inorganic material, such as the silicon-containing material. The encapsulation layeris disposed over the cathode, where the encapsulation layerextends under at least a portion of the overhang structurespast the cathodealong the sidewall of the first structures, and contacts the bottom surface of the second structuresof the overhang structures.

is a schematic block diagram of a methodof forming a sub-pixel circuit, according to one or more embodiments.are schematic, cross-sectional views of a sub-pixelduring the method, according to embodiments described herein. At operationas shown in, a resistis disposed over adjacent PS, adjacent first structures, adjacent second structures, and at least a portion of the protective material. A photolithography process is performed to form a pattern within the resist. One or more gaps are patterned within the resist using the photolithography process. In one or more embodiments, after the photolithography process, a gap extends through the resist. A portion of the protective materialdisposed over the anodeis exposed by the gap. In one or more embodiments, the portion of the protective materialdisposed over the anodedisposed between the adjacent PS.

At operationas shown in, an etching process is performed to remove the portion of the protective materialdisposed over the anodeis exposed by the gap. In one or more embodiments, the etching process is a dry etching process. The resistis removed after the etching process. The etching problem forms the protective layerformed over the adjacent PSand extending under the adjacent first structures. A portion of an upper surface of the anodeis exposed after the etching process. The resistis stripped after the etching process is performed.

is a schematic block diagram of a methodof forming a sub-pixel circuit, according to one or more embodiments.are schematic, cross-sectional views of a sub-pixelduring the method, according to embodiments described herein. At operationas shown ina dry etching process is performed. As depicted ina dry etchant is applied to the sub-pixel circuit. The adjacent overhangs formed by the adjacent second structuresextending past a sidewall of the adjacent first structures. The portion of the second structureextending past the first structuredefines a shadow region. The protective materialis disposed over adjacent PSand extends over an upper surface of the anode.

At operationas shown in, a portion of the protective materialis removed. The dry etchantremoves the portion of the protective material. The shadow region protects a portion of the protective materialdisposed under the second structures. The portion of the protective material disposed under the second structuresand the first structuresdefines the protective layer. An endpoint of the protective layer is vertically aligned with an endpoint of the second structure as shown with the reference line L.

is a schematic block diagram of a methodof forming a sub-pixel circuit, according to one or more embodiments.are schematic, cross-sectional views of a sub-pixelduring the method, according to embodiments described herein. At operationas shown ina wet etching process is performed. As depicted ina wet etchantis applied to the sub-pixel circuit. The adjacent overhangs formed by the adjacent second structuresextending past a sidewall of the adjacent first structures. The protective materialis disposed over adjacent PSand extends over an upper surface of the anode.

At operationas shown in, a portion of the protective materialis removed. The wet etchantremoves the portion of the protective material. The first structureprotects a portion of the protective materialdisposed under the first structure. The portion of the protective materialremaining after the wet etching process defines the protective layer. An endpoint of the first structureextends vertically past an endpoint of the protective layeras shown with the reference line L.

While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.